[Asterisk-Users] Best echo-free and trouble-free system?

[Andrew Kohlsmith]

> Following the "2-wire to 4-wire causes echo" thought, the following
> should not result in noticable echo, true?

> - Analog phone <-> TDM10B-FXS <-> Asterisk <-> TDM01B-FXO <-> PSTN
> - VOIP Phone <-> Asterisk <-> VOIP Phone
> - VOIP Phone <-> Asterisk <-> T100P <-> PRI

All of these have the potential for echo.  Your analog phone is a 2-4 wire 
hybrid (ear and mike -> 2 wire) -- the FXS and FXO modules have 2-4 wire 
hybrids...

I suppose it's more of an issue of quality of the hybrids.  I have been very 
happy with the TDMxxx hybrids, and very unhappy with the X100/101P hybrids.

VOIP phones can throw a DSP at the echo problem and will generally have great 
success since the ear and mike interfaces are pretty much standard -- you 
don't have unpredictable interfaces like you do on the PSTN side.

Regards,
Andrew